This invention provides the compounds of formula (I):
or its a pharmaceutically acceptable ester or amide of such compound, or a pharmaceutically acceptable salt thereof, wherein X
1
is NH; R
1
, R
2
, R
4
through R
6
and R
7
through R
11
are all hydrogen; R
3
is hydroxy; X
2
and X
3
are methylene; X
4
is a bond; and X
5
is a carbon atom, and the like. These compounds have ORL1-receptor antagonist activity; and therefore, are useful to treat diseases or conditions such as pain, various CNS diseases etc.